18.06: Preliminary transition piece design for an onshore wind turbine

Abstract

ABSTRACTSteel lattice structures are rather well established for very tall supporting structures for wind turbines. Recently, fully lattice towers and steel hybrid lattice/tubular towers are being investigated as a possible solution for taller onshore wind turbines for which convectional steel tubular towers are less competitive.The steel hybrid towers require a transition piece to establish a connection between lattice and tubular parts. The transition piece is transferring the loads from the tubular segment at higher elevation to the lattice structure which is fixed to the foundation. It is critical component to design, because non‐standardized solution is necessary to resist cyclic loading in a cost‐effective solution. Well‐designed transition pieces with optimized resistance and feasible for manufacturing and execution on site is important for the market acceptance of a new type of onshore wind towers.This research focuses on the investigation of the transition piece for an onshore wind turbine hybrid tower. The 5MW reference wind turbine and a hybrid lattice/tubular tower was simulated in the servo‐aeroelastic analysis tool (by ASHES software) from which the loads and dynamic response of the supporting structure was obtained. Cross‐section forces at the transition piece elevation were calculated and the connection with the lattice structure is designed.The transition piece was designed by FEM considering ultimate limit load and fatigue load, using nonlinear analysis and hot spot method for life time prediction, respectively. Potential of using high strength steel S690 was investigated.